A Prospective Study of Adequacy of Anticoagulation with Fixed Dose Weight Adjusted Unfractionated Heparin in Patients with Deep Vein Thrombosis

Weight adjusted fixed dose subcutaneous unfractionated heparin (UFH) is one of the options for the treatment of deep vein thrombosis (DVT), but the degree of its anticoagulant effect has not been tested in India. This was a prospective observational study, conducted at a tertiary care hospital in South India between September 2012 and March 2014. DVT was diagnosed using compression ultrasonography. UFH was given as an initial loading dose of 333 U/kg followed by a maintenance dose of 250 U/kg twice daily subcutaneously. aPTT was done on day 2 and day 4 after 6 h of the morning dose of heparin. Patients were categorized based on aPTT ratios. Fifty five patients treated for proximal lower limb DVT had received UFH. Their median age was 41 years. DVT was secondary to malignancy, immobilisation or pro-coagulant state. No obvious etiology was found in 47 % of the patients. The mean aPTT on day 2 was 41.8 s and 51.7 s on day 4. The aPTT ratio was subtherapeutic in 63.6 % and therapeutic in 32.7 % of the patients on day 2. Five patients had adverse events in the hospital. Three patients died and two other patients had confirmed pulmonary embolism. Death was due to pulmonary embolism in one patient and metastatic malignancies in the other two. No bleeding manifestation had occurred. Caution is required in implementing this UFH regimen as this preliminary investigation has found predominantly subtherapeutic aPTT ratios during the initial phase of anticoagulation.